714 



SCIENCE. 



[N. S. Vol. I. Ko. 20. 



Acquired Automatism: The individually 

 modified physiological basis of the perfor- 

 mance of acquired movements or activities 

 which have been stereotj'ped by repetition." 



Professor Morgan points out that there is 

 some overlap in these definitions, but it is 

 difficult to see how such overlaps are to be 

 avoided. H. F. 0. 



S03IE MEANDEBING RIVERS OF WISCONSIN. 



Two years ago Professor Davis* called 

 attention to the wide meanders of the Osage 

 river of Missouri. He said: "The me- 

 anders of the river are pecuHar in not being 

 like those of the Mississippi, spread upon a 

 flat flood-plain. High spurs of the upland 

 occupy the neck of land between everj' turn 

 of the stream. Evidently the meanders are 

 not of the ordinary kind." He explained 

 the pecuUar tortuous course of the river as 

 an inheritance fi'om an earlier cycle, during- 

 which the river had worn the land down to 

 a surface of faint relief. The stream at 

 that time swung to and fro in broad me- 

 anders developed on a wide flood-plain. 

 The whole region was then somewhat ele- 

 vated, and the stream again set to work to 

 cut down its channel to the new baselevel. 

 But the meandering course which it had 

 acquired late in the preceding cycle was 

 carried over into the new cycle of its life. 



A recent visit to a part of the di'iftless 

 area of Wisconsin, Lafayette and Grant 

 counties, gave me an opportunity of ob- 

 serving a similar habit of some of the 

 rivers of that region. The general surface 

 of the country is that of a gently rolling- 

 plain, at an elevation of from 850 to 1000 

 feet, A. T. The interstream surfaces are 

 broad and slightly undulating, but well 

 drained. The surface rock, except in the 

 immediate vicinity of the streams, is the 

 G-alena limestone. Occasionally the gen- 

 eral level of the top of the country is 



*SciENCE, April 28, 1893, vol. xxi., p. 225 et seq. 

 Science, November 17, 1893, vol. xxii., p. 276 et seq. 



broken by hills, which rise 200 to 300 feet 

 above the general level. The highest of 

 these are capped by the hard Niagara lime- 

 stone; the lower by beds of the Cincin- 

 nati group. These hills foi'm the so-called 

 'mounds,' of which, in the area visited, the 

 Platte Mounds— 1250-1.300 feet, A. T.— are 

 the highest. The hard N"iagara limestone 

 caps of these mounds are the remnants of 

 beds which formerly stretched over all this 

 region, and which has since been removed 

 by denudation. To hills of this type Prof. 

 Davis has given the name, Monadnocks. 



The rocks of this region are nearly hori- 

 zontal, and in general there is not a sharp 

 contrast between the slant of the beds and 

 the general slope of the upland surface. It 

 seems, therefore, as if the upland might be 

 a structural plain due to a resistant stratum, 

 the Galena limestone, at the level of the 

 upland — a stratum which had been revealed 

 by denudation of the overlying beds. If 

 this were the case, the upland level would 

 be independent of any former baselevel. 

 But such a conclusion does not seem to be 

 admissible ; although nearly horizontal, the 

 limestone has been bent into gentle flex- 

 ures, some of which are sufiicient to bring 

 the underlying Trenton limestone and St. 

 Peter's sandstone up to the level of the 

 upland surface. The plain is continuous 

 across these low arches and bevels the 

 edges of the gently inclined beds. More- 

 over, to the north of the outcrop of the 

 Galena limestone, the upland plain bevels 

 the gently inclined edges of the underlying 

 formation, which there come to the surface. 

 In that region, however, the plain is now 

 more completely dissected than further 

 south. Whatever coi-respondence exists 

 between the inclination of the beds and the 

 slope of the plain is fortuitous and not due 

 to structure primarily. It is believed that 

 this plain is a surface of denudation, the 

 result of long continued erosion on a 

 greater land mass when the land stood lower 



